Video ads should not be auto-playing sound. I hate auto-playing audio and always turn them off in the network settings. However, the scammers still slip through the network (generally the network shuts them down as soon as they're discovered). So that is likely what is happening here. In order to shut it down, I need to report it to the network, and they generally need the destination url. If you can right click on the video ad and select 'copy link' or similar, then PM me the link and I'll report it to the network.